package demo00;
class Keyboard implements USB {
    @Override
    public void open() {
        System.out.println("键盘USB接口开启");
    }

    @Override
    public void close() {
        System.out.println("键盘USB接口关闭");
    }

    public void knock() {
        System.out.println("键盘敲击");
    }
}